A tick (Ixodida) – carrier of several human and animal diseases, for example, dangerous Lyme disease, babesiosis, anaplasmosis, Powassan virus disease and many others.
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Pfizer said Monday it will seek regulatory approval for a Lyme disease vaccine candidate despite the failure of a late-stage trial.
Pfizer said the vaccine failed to meet the trial’s statistical goal because not enough people in the study had Lyme disease to have confidence in the results. Still, the company said the shot reduced the infection rate by more than 70% in people who received the vaccine compared to the placebo, an effectiveness that the company says is strong enough to present to regulators.
“The greater than 70% effectiveness demonstrated in the VALOR study is very encouraging and provides confidence in the vaccine’s potential to protect against this can be debilitating disease,” Annaliesa Anderson, Pfizer’s chief vaccines officer, said in a statement.
A Lyme disease vaccine is unlikely to become a bestseller for Pfizer, with the company’s partner Valneva estimating its peak annual revenue at $1 billion. Pfizer expects overall revenue of around $60 billion this year, with its Covid-19 vaccine accounting for more than $5 billion of that forecast.
But Pfizer had touted the Lyme vaccine results as one of its key enablers this year, and it presented an opportunity to introduce the only human Lyme disease vaccine.
Moving forward with a shot that technically failed a clinical trial under an administration that has preached tighter control of vaccines could prove risky for Pfizer, and it could serve as a litmus test for U.S. vaccine policy.
Lyme disease is an illness caused by a bacteria most often transmitted to humans by ticks. This can cause arthritis, muscle weakness and pain. About half a million Americans are diagnosed or treated for Lyme disease each year, according to estimates from the Centers for Disease Control and Prevention.
Despite the prevalence of the disease, particularly in the Northeast, there is no vaccine available for humans. A company that would later become GSK introduced a vaccine called LYMErix in 1998, but withdrew it only a few years later after public concerns about safety diminished. This experience hampered the development of Lyme disease vaccines for humans, although several companies now make them for dogs.
Pfizer and Valneva have also experienced setbacks. By 2023, the companies dropped about half of the Phase 3 trial participants due to quality issues with the clinical trial site’s third-party operator Care Access. The trial initially enrolled about 18,000 people and, after budget cuts, ended with about 9,400 people.
The companies’ vaccine targets protein A on the outer surface of the bacteria that causes Lyme disease. A vaccinated person creates antibodies that are transmitted to a tick and prevent the bacteria from being transferred from the tick to humans. The series includes three injections the first year, then a booster dose the following year.
The companies said they observed no safety issues during the trial.